Bandvagn 206

Hägglunds Bv 206 Sweden's two-car tracked carrier is the amphibian most people never think of as one. Its ground pressure is so low it can cross loose snow without sinking, and when it reaches open water it simply keeps going, its tracks pushing it along at about 3 mph. That swim is slow, but it is only there so a river or a flooded bog never becomes a dead end. Production began in 1980, more than 11,000 have been built, and armies in over 37 countries have used them. Retired ones now haul crews to remote oil wells, wildfire lines and rescue jobs, which is about as good a proof of a working design as this list asks for.